Adding new flags?

Igor Tarasov wrote:
> 2009/4/10 Nikolay Sivov <bunglehead at gmail.com>:
>>> Igor Tarasov wrote:
>>>>> Hi there!
>>>>>> I try to implement as precise as possible one undocumented feature in
>>> comctl32, this all deals with one structure field. After lots of
>>> testing I know the following:
>>>>>> 1. Default value for that field returned by getter is 0.
>>> 2. By default it is ignored in behavior.
>>> 3. If you change value by the setter, even to 0, behavior changes.
>>> 4. Negative values, such as (-1) also produce different behavior and
>>> cannot be used as "field not changed" flag.
>>>>>> So, does that mean that I have to add new flag to the structure that
>>> would be set only if that field is changed, or there is another way to
>>> do that?
>>>>>>>>>>> What flag are you speaking about? Toolbar stuff?
>>>>>> Yep, it's about undocumented feature of iBitmap controlling buttons'
> size But it works only if cx is zero and iBitmap was not specifically
> set.
>>So (-1) for iButton is reserved for not using imagelist bitmap at all
and in some places this value checked for <0 instead of
== -1, right? Does it apply for separators only? If not maybe it's
better to add something like BOOL IsiBitmapValid.
Let's get another opinions. (Hope you'll be ready with patch for today
release)